The gap between renting and owning with a conventional mortgage, even a high loan-to-value mortgage, has become unbridgeable for low and modest income families in some parts of the country, not just London.

Take Cambridge as an example. A couple with one child with a net income of £22,000 would have to spend 85% of their income on monthly mortgage payments if they had a 95% mortgage on a two-bedroom property. While the barriers to ownership are high, the aspiration to own remains strong, and there are good reasons to promote ownership, not least the fact that welfare spending on housing benefit and pensions will rise dramatically if large numbers enter retirement and still have to pay rent. Shared ownership can act as a bridge to home ownership for those on lower incomes, but to meet the needs of millions not a few hundred thousand, the product would need to change and be massively scaled up.

Today's shared ownership product is the result of attempts to meet the requirements of all of the parties involved: government, local authorities, lenders and housing associations – but not principally consumers. When housing associations found themselves with shared ownership properties they could not sell after the financial crisis, several converted them to rent-to-buy to meet their needs more than to satisfy a customer demand. Five years on, many of those tenants have not saved a deposit to become shared owners. If shared ownership is to become the fourth tenure of housing in the UK – alongside homeownership, private rent and social rent – this needs to change.

Many of today's rules and regulations need to be stripped back and replaced by a simpler set of standards that are transparent, easy to understand and allow for greater flexibility, and housing associations need to design the product around the needs of potential buyers better.

Meeting customer demand for shared ownership means designing a product for two very distinct populations: those who staircase to full ownership and those who remain part owners. Those who can staircase need stronger incentives and lower barriers to doing so, much as Thames Valley Housing's shared ownership plus or Gentoo's Genie home purchase plan offer. Those who remain part owners need to know that the equity they have accumulated is indeed theirs as long as they are not in arrears and need to be able to move within shared ownership as their life changes. Making moving easy for long term shared owners will only be possible if we can increase the supply of shared ownership properties.

This means both more new-build properties and also more opportunities for people to purchase a share of an existing property – what used to be known as "do it yourself shared ownership" but is now rare.

A big increase in scale will need support from government. Given that investment in shared ownership is released once shared owners staircase, the Homes and Communities Agency could invest on the assumption that it would be repaid in the long term as properties are sold. Given that shared ownership is generally needed in high price areas, there is also a realistic expectation of capital gains. Housing associations also need to work more closely together to develop large-scale portfolios that will attract institutional investors into the market. Finally, local authorities need to use their public land and planning policies to enable the development of more shared ownership in those areas where large numbers of working people are priced out of conventional ownership. In an era of 40% cuts, making strategic use of land in this way can be tough for local authorities struggling to balance the books. But if best value continues to mean highest price, the aspirations of many low and modest income working people cannot be met.